1. Field of the Invention
The present invention relates to a push switch including a light-illuminating structure for a lockout of a power window. More specifically, the present invention relates to a push switch having a fixed contact unit on the inner surface of a case and a movable contact unit that comes into contact with and separates from the fixed contact unit on an operation shaft.
2. Description of the Related Art
The structure of a first known push switch including a light-illuminating structure described in Japanese Unexamined Patent Application Publication No. 63-168932 is illustrated in FIG. 9.
As illustrated in the drawing, the push switch includes a push button 21 having a transparent display portion on the front surface, a non-transparent escutcheon 23 having a button hole 22 for passing through the push button 21, a non-transparent printed circuit board 25 being disposed on the back side of the escutcheon 23 and having a switch 24 operated by the push button 21 on the front side, a light-guiding portion 26 extending from the back of the push button 21 and being passed through a hole on the printed circuit board 25 formed behind the push button 21, and a light source 27 disposed on the back side of the printed circuit board 25.
The known push switch has a structure that guides light from the light source 27 that is disposed outside the push button 21 to the push button 21 to be operated, and the usability of light is low.
Since a long light-guiding portion 26 has to be formed as a single piece with the push button 21, the production cost per component unit is expensive.
Moreover, since the light source 27 is disposed on the side of the lower portion of the light-guiding portion 26, the diameter of the push switch has to be large when viewed from above to sufficiently illuminate the display portion.
In a push switch according to an embodiment of the present invention, the display portion and the light source are disposed close to each other. In this way, the display portion can be efficiently illuminated and the diameter of the push switch can be reduced.
A second known push switch is disclosed in Japanese Unexamined Patent Application Publication No. 2003-51225 and is illustrated in FIGS. 12 and 13.
As illustrated in the drawings, a case 31 includes sidewalls 31a, a rear wall 31b, and opening ends 31c. A pair of depressions 31d and a pair of protrusions 31e are provided on one of the sidewalls 31a close to the opening ends 31c. 
A fixed contact unit 32 includes flat bases 32a, holes 32b formed substantially in the center of the bases 32a, fixed contacts 32c extending perpendicularly from one end of the bases 32a, and terminals 32d extending perpendicularly from the other end of the bases 32a. 
The fixed contact unit 32 is mounted by passing the protrusions 31e of the case 31 through the holes 32b and aligning the bases 32a in the depressions 31d by thermal caulking.
A return spring 33, which may be a coil spring, is disposed in a manner such that one of the ends urges the rear wall 31b inside the case 31.
A movable unit 34 includes a base 34a and a prism-shaped operation shaft 34b that protrudes outwards from a front wall 34c of the base 34a. The base 34a includes the front wall 34c, a rear wall 34d, a first sidewall 34e, a second sidewall 34f, and a third sidewall 34g. A circular hole 34h is formed substantially in the center of the third sidewall 34g. The base 34a has a space (not shown in the drawings) defined by the front wall 34c, the rear wall 34d, and the first, second, and third sidewalls 34e, 34f, and 34g. The operation shaft 34b includes a pair of first side surfaces 34q, a pair of second side surfaces 34j, a pair of engagement protrusions 34k, supports 34m including four projections, and a tip 34n. 
The base 34a of the movable unit 34 is disposed inside the case 31. At this time, the return spring 33 is interposed between the space (not shown in the drawings) of the base 34a and the rear wall 31b of the case 31. The movable unit 34 is urged by the resilient force of the return spring 33 in the axial direction of the movable unit 34.
A first end of a driving member 35 is attached to one of the sidewalls 31a of the case 31. A second end of the driving member 35 is passed through the sidewall 31a of which the first end is attached to and is attached to the second sidewall 34f of the movable unit 34. At this time, a heart cam (not shown in the drawings) is provided on the second sidewall 34f where the second end of the driving member 35 is provided. The second end of the driving member 35 moves inside the heart cam. As a result of the movement of the driving member 35, the movable unit 34 moves along a predetermined trajectory.
A flat spring 36 is made of a resilient flat metal piece that is substantially L-shaped. The flat spring 36 has an attachment portion 36a and a pressed portion 36b extending orthogonally from one of the ends of the attachment portion 36a. The pressed portion 36b is disposed in a manner such that the pressed portion 36b urges the driving member 35 toward the sidewall 31a. 
A resilient member 37, which may be a coil spring, is passed through and stored in the hole 34h of the third sidewall 34g of the movable unit 34.
A movable contact unit 38 includes a base 38a, two substantially oval movable contacts 38b, a pair of attachment portions 38c extending orthogonally from the outer edges of the base 38a, blades 38d, and guiding pieces 38e. A first end of the resilient member 37 is urged against the movable contact unit 38. The base 38a opposes the third sidewall 34g of the movable unit 34. At this time, the pair of attachment portions 38c is interposed between the front wall 34c and the rear wall 34d. In this way, the two movable contacts 38b are urged in a direction away from the third sidewall 34g of the movable unit 34 by the resilient force of the resilient member 37.
The two movable contacts 38b are urged against the fixed contacts 32c of the two fixed contact unit 32.
A knob 39 is made of synthetic resin and is formed by a coinjection molding process. The knob 39 includes an inner chassis 40 and an external chassis 41 covering the inner chassis 40. The inner chassis 40 and the external chassis 41 are formed as a single piece. The knob 39 is disposed in a manner such that the prism-shaped operation shaft 34b of the movable unit 34 is disposed inside a prism-shaped attachment portion 40a of the inner chassis 40. In this way, the knob 39 is attached to the movable unit 34. When the knob 39 is attached to the movable unit 34, the pair of engagement protrusions 34k of the movable unit 34 is latched to a pair of engagement holes 40b of the inner chassis 40 of the knob 39.
Next, the operation of the push switch is explained briefly. First, when the knob 39 is pressed down, the knob 39 and movable unit 34 are pushed downward against the resilient force of the return spring 33. In this way, a part of the movable unit 34 is pushed into the case 31. When the movable unit 34 is pushed into the case 31, the two movable contacts 38b of the movable contact unit 38 are urged against the fixed contacts 32c of the fixed contact unit 32. Accordingly, the push switch is turned on.
At this time, the driving member 35 moves along a predetermined trajectory in the heart cam (not shown in the drawings) provided on the second sidewall 34f of the movable unit 34. Subsequently, when the knob 39 is pushed in further, the knob 39 and the movable unit 34 are also pushed in further. Then, when the pressure on the knob 39 is released, the knob 39 and the movable unit 34 return to their original positions due to the resilient force of the return spring 33. Accordingly, the push switch is turned off.
In such a known push switch, the blades 38d are provided at both sides of the base 38a of the movable contact unit 38. These blades 38d slide through guiding grooves in the case 31. The guiding grooves have bumps at positions deeper inside the case 31. In this way, when the push switch is pushed down, the movable contacts 38b of the movable contact unit 38 are separated from the fixed contacts 32c. Consequently, the sliding life of the push switch can be extended.
However, because the blades 38d are provided at both sides of the base 38a of the movable contact unit 38, the size of the push switch in the movement direction of the movable unit 34 and the direction orthogonal to the movement direction cannot be reduced. As a result, the size of the push switch becomes large.